Electric welder



Aug. 25, 1942. c. A. NICHOLS ELECTRIC WELDER Filed April 9, 1941 8 Sheets-Sheet l V INV'ENTOR 44 MM wm p Aug. 25, 1942. c. A. NICHOLS ELECTRIC WELDER 8 Sheets-Sheet 2 Filed April 9. 1941 2: I 4 gym-r02 Y 07%, 75.; A'r'rdRNEm/ g- 25, 1942- c. A. NICHOLS 2,293,846

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Patented Aug. 25, 1942 ELECTRIC WELDER Charles A. Nichols, Anderson, Ind; assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application April's, 1941, Serial No. 387,565 (c1. 219 s) j 6 Claims.

This invention relates to the manufacture of electrically welded steel tubing.

The object of the invention includes .the provision of an improved electric welding machine of simple and durable construction which may be manufactured at low cost.

.Further objects and advantages of the pres.

ent invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown. 7 v

In the drawings:

Fig. 1 is a side elevation partly in section showing a welding machine embodyingthe present invention;

Fig. 2 is a view taken in the direction of the arrow 2 of Fig. l, and is partly in section;

Fig. 3 is a view taken in the direction of arrow of Fig. l;

Fig. 4 is a plan view;

Figs. 5 and 5a provide a fragmentary longitudinal sectional view on the line 5-5 of Fig. 4 and is drawn to a larger scale than Fig. 4;

Fig. 6 is a longitudinal sectional view of the transformer of which a fragmentary sectional "view appears in Fig. 5;

Fig. 7 is a sectional view on the line 11 of Fig. 6;

Fig. 8 is a view looking in the direction of ar-' Fig. 9 is a view in the direction of arrow 9 of Fis.

Fig. 10 is a sectional view on the line llll0 of Fig. 8; a

Fig. 11 is a fragmentary view partly in section showing the front elevation of the pressure roll which appears in a smaller scale in Fig. 2 below the welding roll; and

Fig. 12 is a plan view of the part shown in Fig. 11 and is partly in section, the section being taken on the line l2|2 of Fig. 11.

The apparatuslcomprises a box-like base 20 of Fig. 1 provided with a door 2! in the left wall Referring also to Fig. 2, the base 20 supports four tubular bearings 22 for guiding vertically movable rods 23, the lower ends of which are attached to a spider 24, provided with nuts 25 for receiving screws 25 provided by a shaft 21 attached to worm wheels 28 supported by step bearings 29, (Fig. 1') resting upon the top of the base 20. Worm wheels 28 mesh with worms 30 connected with a shaft 31 supported by hearing brackets 32 attached to the underside of the top amount of expansion and contraction. But,

of the base 20. Shaft 3| has a squared end ,33

The rods 23 support a frame 40 insulatingly supporting at its ends bearing brackets 40A and 40B. Micarta insulating plates 40X space the brackets 40A and 40B from frame 40. Bracket 40A supports ball bearings 4| (Fig. 5) which are secured between retainer plates 42 and 43 secured to a ring 44 which is fixed to the annular bearing boss 45 integral with the bracket 40A. The inner races of the ball bearings 40 are clamped together and are confined between a shoulder 45 of a tubular shaft 41 and a nut 48 threaded on said shaft. Shaft 41 is freely rotatable but can not move axially with respect to bracket 40A. Shaft 41.- which. is made of pure copper, is mounted upon shaft 50 also of pure copper and is insulated therefrom by non-conducting member including asleeve 5| of laminated Bakelite tubing.

Shaft 41 is provided with stainless steel inserts 52 for receiving screws 53 by which welding electrode 54 is attached to shaft 41 and is electrically connected therewith. Likewise shaft 50 grooves 59 in order to increase the radiating surface. Streams of water play upon these grooves in order to cool the electrodes.

Screws'52 secure to the bearing bracket 40B bearing retainers 50 and GI between which a pin or small diameter roller bearing 53 is confined.

The inner race 64 of which has a snug sliding fit with a reduced portion 65 of shaft 50. Thus, bearing 63 supports the right end of the shaft 50 but permits longitudinal movement thereof due to expansion and contraction with changes in temperature. The length of the shaft 50 between the bearing brackets 40A and 40B i relatively long therefore there will be an appreciable practically all of this expansion'and contraction takes place between the bearings 41 and 53. As the distance between the bearing 4| and electrodes 54 and 51 is relatively short the expansion of the shaft between the bearings and the electrodes is practically negligible.

A disc of pure copper 10 is attached by screws 1| to the flange 12 of shaft 41. The disc and shaft are electrically connected by screws 'II and by pins Ila insulated from and drivingly connected with flange 50a of shaft 50. Disc I is insulated from shaft 50. Shaft 50 supports and is electrically connected with a disc of pure copper I3 mechanically and electrically connecting with the disc I0 by rods 14 of pure copper secured in position by copper nuts I5. The space between the discs I0 and I3 and between the shaft 50 and the rod I4 is occupied by a cylindrical, laminated transformer core I6 and a transformer primary 11 comprising a plurality of four-layer turns of flexible copper ribbon separated by insulating ribbons I9 The core I6 is suspended from the rods I4. As shown in Fig. 7 the core I6 extends through two aluminum spiders 80 of annular formation and integral with lugs 8|, spaced 90, and each provided with a socket 82 at its outer end for receiving a set screw 83 passing through a threaded hole in a rod 14. The primary and core assembly are insulated from the discs I0 and I3 and from the shaft 50 by non-conducting plates 85 and 86 and non-conducting sleeve 81.

The ends of primary 1! are connected by leads 90 and 9| with copper rings 92 and 93, respectively, insulatingly supported by a sleeve 94 and clamped thereon by a nut 95. The rings 92 are insulated from each other from the sleeve, from the nut 95 and from' a spacer 96. Sleeve 94 is connected with shaft 50 by a key 91. The sleeve 94 is split by saw-cut at 98 and by saw-cut at 99 to provide a resilient clamping portion I00 cooperating the screws IOI which cause this clamping portion to grip the shaft 50. The secondary of the transformer is a single turn circuit comprising electrode 51, shaft 50, disc I3, rods I4, disc I0, shaft 41 and electrode 54.

Each collector ring 92 and 93 is engaged by two brushes I02 guided by brush holders I03 and urged by springs I04 into engagement with their respective collector rings. The brush holders I03 are supported by brackets I05 insulated from each other and insulatingly supported by bearing bracket 40B. Each brush holder I03 has a threaded part I06 threaded through the bracket I05 and engageable with a nut I0'I for attachment of a terminal clip I08 connected with a cable I09.

As shown in Fig. 5, the tubing T to be welded passes between the Welding electrodes 51 and 54 and a supporting or back-up roller IIO having a flange III engageable with only one electrode. The roller I I0 which is made of copper is attached by screws II2 to the flange II3 of a shaft II4 journaled in ball bearings II5 carried by forked races of which are supported by a sleeve I2I attached to a bracket I22 which is carried by a horizontal plate I23 resting on table 20. Roller H0 is caused to exert uniformly constant pressure upon the tubing T by the use of weights I24 attached at I26 by a cable I to lever I I6. While the roller H0 is thus exerting the desired constant upward force upon the tubing T to secure proper welding pressure between the tubing and the electrodes, the roller IIO cooperates with the tubing T in the manner of a trolley wheel with a trolley. In other words, th roller I I0 follows the tubing T and takes whatever position the tubing T may require due tothe minute variations in shape or diameter. This welding machine is particularly adapted for welding, small diameter steel tubing according to the method disclosed in 75 midway with the electrodes.

the copending application of Charles A. Nichols, Serial No. 384,563, filed March 21, 1941. To successfully weld small diameter tubing it has been found expedient to form the .tubing out of round in order that it may be guided by guide wheels having grooves similarly formed so that the seam of the tube will be always on top or in alignment with the insulation plate 58 between the electrodes 54 and 51. The grooves provided by .the electrodes and the groove provided by the roller IIO are shaped so as to accommodate the tubing which is slightly elliptical so that the tubing is welded out of round after having been formed out of round. As disclosed in the Nichols application, after welding takes place, the bead of excess metal at the seam is removed by a scarfing tool located vertically above the tubing. Obviously, the skewing or spiralling of the tubing must be prevented in order that the bead will always be moved into contact with the scarfing tool. Even after all of these precautions are taken to prevent skewing of the tubing, it sometimes happens that the tubing will spiral slightly thus displacing its seam from th vertical plane I have discovered that such spiralling may be eliminated by slightly angularly displacing the plane of rotation of the,

central groove of .roller' IIO from the plane of rotation of the median-line of insulation sheet 58. This is accomplished by moving the plate I23 about a pin I30 having a threaded shank I3I receiving a nut I32 by which the pin I30 is attached to the table 20. The axis of the pin is vertical and is represented by the point I30X (Fig. 12) intersecting the median line IIO-Y of the groove in roller I I0 and passing vertically upward as indicated by line I3I-X (Fig. 5) and intersecting the axis of the tubing T and. the median line of the groove provided by the electrodes 54 and 51. This adjustment may be effected by turning adjusting screws I33 (Fig. 12) each threaded through a lug I34 attached to table 20 and engaging lug I35 attached to plate I23.

During the continued use of the machine the tube-receiving groove provided by the electrodes becomes roughened and worn out of true due to the intense heat of the electric current passing between the electrodes and the tubing. This groove may be trued or resurfaced by the use of a cutting tool I which is part of a groove cutting apparatus I 4| mounted upon the bearing bracket 40A. Before using the groove cutting apparatus I 4I the outer cylindrical surfaces of the electrodes are trued by a tool I42 mounted in a tool holder I 43 of the conventional type also supported by the bearing bracket 40A. While truing the electrodes they should be elevated above the roller I I0. Before frame 40 is elevated by turning the handwheel 34 (Fig. 1), a shaft I44 (Fig. 12 is turned by a wrench fitting on the squared end I45 thereof in order to move an eccentric cam I46 (Fig. 11) under that portion of the lever II6 extending to the right of the bearing pin 1. The eccentric II6 then receives the pressure exerted by weights I24 and upward movement of roller H0 is prevented while the electrodes are being elevated preparatory to trimming.

While the machine is welding tubing the electrodes are rotated by movement of the tubing T between them and the rollers I I0. The tubing T is propelled by the forming rolls which contact with the tube prior to welding and by the rounding or truing rolls which contact with the tube after welding. But, when the electrodes are being trued, they are rotated by a separate source of power comprising an electric motor I50 (Fig. 1) mounted on a frame I5I containing a gear reducing mechanism connecting the motor I50 with a shaft I52 attached to a pulley I53 connected by belt I54 with a pulley I55. Frame I5I is supported by frame 40. Pulley I55 (Fig. is journaled on a bearing I55 provided by retainer plate 5|. Pulley I55 (Fig.8) pivotally supports at I51 a plurality of pawls I58 urged by leaf springs I 59 into engagement with a fine tooth ratchet I50 connected by keys I5I with the extension 55 of shaft 50. Leaf springs I50 are fastened to the heads of the screw I55a attached to pulley-I55. During welding the ratchet I50 rotates counterclockwise (Fig. 8) and the teeth thereof merely move under the pawls I55 which ride upon them with light pressure. When the electric motor drives the pulley I55 counterclockwise (Fig. 8)- motion is transmitted from the pulley to the shaft 50 through the pawls I53 the ratchet I50.

The ratchet I50, Fig. 5, is retained by a washer I52 and a nut I53 threaded in the shaft 50. The nut I53 is integral with a pipe coupling I54 welded to a tube I55 extending through a central hole I55 in shaft 50 and terminating near the plug I51 in the left end of the shaft 50, Fig. 5. Water for cooling the shaft 50 enters through "a passage I55 and flows through the tube I51 and then back around the outside of the tube toward the right and out through a passage I50 in plug I53. Plug I53 includes an extension I10 (Fig. 5a), around which is swivelled a conven tiomal two-hose fitting (not shown) having separated annular ducts cooperating with side inlet I550 and side outlet I53a of the extension I10.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows: a

1. An electric welder comprising rotatable electrode discs separated by insulation and together providing a groove for receiving a butt-seam tube an axis generally paralleling the axis of rotato :be welded, a grooved tube supporting roller for retaining the tube against the electrodes and rotatable about an axis generally paralleling the axis of rotation of the electrodes, a lever rotatively supporting the roller, means for exerting a constant force upon the lever to urge the roller 2 against the tube and the tube against the election of the electrodes, means for supporting the roller with its axis substantially vertically below the axis of the electrodes, said means comprising alever supporting the roller at one end, a bracket pivotally supporting the lever on a horizontal axis intermediate its ends, a weight connected with the other end of the lever in order to force the roller upwardly against the tube with constant pressure and a bearing swivelly supporting the bracket for rotation about a vertical axis spaced from the horizontal axis of the lever and at right angles to the axes of rotation 01. the electrodes and the roller.

3. An electric welder comprising electrode discs rotatable on a horizontal axis separated by insulation and together providing a groove for receiving a butt-seam tube to be welded, a grooved tube supporting roller for retaining the tube against the electrodes, means for supporting the roller with its axis substantially vertically below the axis 01' the electrodes, said means comprising a lever supporting the roller at one end, a bracket pivotally supporting the lever on a horizontal axis intermediate its ends, a weight connected with the other end. of the lever in order to force the roller upwardly against the tube with constant pressure, bearing swivelly supporting the bracket for rotation about a vertical axis spaced from the horizontal axis of the lever, a bracket supporting the bearing and rotatable about a pivot vertically below the axis of the electrodes and means for adjusting the last mentioned bracket about its pivot.

4. An electric welder comprising electrode discs separated by insulation and together providing a groove for receiving a butt-seam tube to be welded, a grooved tube supporting roller for retaining the tube against the electrodes, means for rotatively supporting the roller with its axis substantially parallel to the axis 01' the electrodes, and provisions for adjusting said means whereby the axis of the roller may be angularly displaced, relative to the axis of the-electrodes, about an axis which intersects the axis of the tube where the tube contacts with the electrodes.

5. A welder according to claim 4 in which the roller supporting means includes a lever for rotatively supporting the roller, a bracket for pivotally supporting the roller about an axis parallel to the roller axis but. spaced therefrom and a bearing for supporting the bracket for rotary movement about an axis at right angles to the axis of the lever and spaced therefrom.

6; A welder according to claim 4 in which the roller supporting means includes a lever for rotatively supporting the roller, a bracket for pivotally supporting the roller about an axis parallel to the roller axis but spaced therefrom and hav-' ing a tubular sleeve whose axis is at right angles to the lever axis and is spaced therefrom, and a bearing for rotatively and axially supporting said sleeve.

CHARLES A. NICHOLS. 

